In this paper, thermal and mechanical properties of ablative thermal protective material (TPM) as inhibitors for a free-standing propellant grain based on phenolic resin (PR) and acrylonitrile butadiene rubber (NBR) were investigated. NBR elastomerized PR composite, reinforced with chopped carbon fibers (CFs) (PR/NBR/CF), was prepared by homogenization of 90 parts by weight (PBW) PR in 100 PBW NBR (28 wt.% of acrylonitrile content). PR/NBR/CF composite was blended in two-roller open and closed mixers and in a twin-screw extruder. Carbon black, aluminum(III)-oxide, and fumed silica were added as promoters of thermal and mechanical properties of PR/NBR/CF. The structural analysis was studied using Fourier transform infrared spectroscopy (FT-IR). Thermal properties of the prepared PR/NBR/CF composite inhibitor were studied by ablation and firing tests, while a morphological analysis of the char layer formed after the ablation test was conducted via scanning electron microscopy (SEM). A low erosion rate of 2.00 × 10⁻⁴ m·s⁻¹ and high tensile strength and elongation at break of 6.7 MPa and 419.92%, respectively, indicate that the developed materials can be applied as a thermal insulation/inhibitor of free-standing rocket propellant grains. Bond strength between PR/NBR/CF composite and aluminized composite rocket propellant (ACRP), determined via a standard peel test, showed higher adhesion forces between the PR/NBR/CF composite and the ACRP compared to the cohesion between the ACRP molecular chains.

The removal of the As(V) and Iprodione fungicide onto EGS@APTES-GT, obtained by amino-modified expanded glass spheres (EGS) modified with goethite, was studied in this work. Material characterization was performed using SEM/EDS, XRD, and FTIR techniques. The adsorption capacities of 51.01 and 94.28 mg g⁻¹, for As(V) and Iprodione removal at 25 °C, respectively, were achieved. A kinetic study indicated lower intraparticle diffusional transport resistance. Physisorption is the dominant mechanism for Iprodione removal, while surface complexation is for As(V). The disposal of effluent water after five adsorption–desorption cycles was attained through Iprodione photocatalytic degradation and arsenate precipitation. Exhausted EGS@APTES-GT, processed by goethite acidic dissolution and grinding, was used as a reinforcing filler in composites production based on commercial unsaturated polyester resin (UPe). An improvement in the mechanical properties was observed, with a gradual increase in the tensile strength, reaching a maximum of 25.9% for UPe with 10 wt.% of ground exhausted adsorbent compared to pure UPe. The overarching concept is defined by the aspiration to develop technologies that address all output flows of advanced processes. Thus, the combination of wastewater treatment technologies and the production of potentially marketable composites successfully achieved both a low environmental impact and the implementation of a circular economy.

Unsaturated polyester resins (UPRs) were synthesized from camphoric acid and diluted with styrene, partially replaced (up to 30%) by trimethylolpropane triacrylate (TMPTA). Rheological tests showed increased but sustainable viscosity due to TMPTA’s higher polarity. These UPRs served as matrices for composites reinforced with non-woven bamboo and flax mats from recycled waste. Mechanical testing revealed that C_f-UPR/TMPTA30 exhibited the highest tensile strength (25.2 MPa) and modulus (0.96 GPa), compared to 18.7 MPa and 0.74 GPa for the styrene-based resin, respectively, attributed to greater cross-link density. Bamboo composites showed lower tensile properties (13.6 MPa) due to random fiber orientation and porosity, while flax-reinforced systems, especially C_f-UPR/TMPTA30–FLAX, reached 42.7 MPa tensile and 95.5 MPa flexural strength, indicating synergy between TMPTA-modified resin and flax fibers. Dynamic-mechanical analysis confirmed stable thermo-mechanical behavior, and water uptake tests showed reduced absorption (by ~10%), suggesting improved fiber/matrix adhesion. SEM images revealed brittle fracture and fiber pull-out in styrene systems, but fiber breakage and ductile textures in TMPTA-based ones, proving better stress transfer. Thermal analysis indicated slightly earlier degradation onset for TMPTA-modified resins but higher char yield in fiber composites. Overall, TMPTA substitution and flax reinforcement enhance the mechanical, interfacial, and thermal properties of bio-based UPRs, supporting sustainable high-performance composites.